1. Field of the Invention
The present invention relates to a dosing head for dispensing a fluid product in the form of doses of predetermined volume, and in particular, a cosmetic product such as a shampoo, a conditioner, a gel, a lotion, a milk, etc. The invention also relates to a packaging and dispensing assembly equipped with a dosing head according to the present invention.
2. Discussion of the Background
In the cosmetics field in particular, a good number of hair products, particularly shampoos, are packaged in containers having deformable walls, the neck of which is closed off by a wall pierced at its center by one or more small holes for expulsion of the product. In order to dispense the product, the container is turned upside down. Pressure exerted on the deformable walls of the container allows the product to be forced out through the hole or holes. The product is collected in the user's palm and applied to his or her hair. However, this simple operation does not allow the amount of product dispensed to be dosed.
Of course, there are devices for dosing a product to be dispensed, but these have a complexity such that their cost is inconsistent with the economic requirements of certain distribution channels, in particular the mass market.
U.S. Pat. No. 5,090,600 describes a dosing head having a dosing chamber formed inside a piston, a free end of which is provided with openings capable of allowing dosed expulsion of the product. The openings in the dosing chamber are exposed by means of pressure exerted by the product on one face of the piston. The product then flows under gravity, through the exposed openings. Such a head is particularly appropriate for the dosed dispensing of low viscosity or "very liquid" products, such as drinks. On the other hand, such a system cannot easily be used for dispensing more viscous products, such as those normally used in the cosmetics field. This is because the viscosity of these products does not allow the dose of product to flow sufficiently under the effect of merely its own weight. Furthermore, the openings are formed from holes which are pierced in the wall of the dosing chamber, and which are therefore oriented radially with respect to the section of the said dosing chamber. Thus, when being expelled, the product leaves with an essentially radial component, which may be acceptable when the product flows merely under the effect of its own weight. On the other hand, such a radial expulsion is completely unacceptable when the product is expelled under pressure, insofar as it becomes very difficult to collect the dispensed product in a localized manner.
U.S. Pat. No. 2,904,227 describes a head for the dosed dispensing of a product, comprising a dosing chamber inside which a piston is slidably fitted. An axial channel passes through the piston and terminates near the free end of the piston in a radial portion which emerges in an outlet. In the rest position, the outlet is closed off. In order to dispense a dose of the product, the outlet is exposed due to the pressure of the product being exerted on the piston. The product flows through a radial portion of the channel, into the axial part of the channel and leaves through the radial outlet. In the same way as in the case of the device in the previous document, the product leaves with a very high radial component, which therefore does not allow localized dispensing of the product. Particularly in the case of a cosmetic product, it is difficult to collect the dispensed product in one's palm. Furthermore, since the product necessarily passes through this axial channel made inside the piston, the device is particularly unsuitable for high flow rates, particularly in the case of products having a high viscosity. In addition, such an axial channel is subject to fouling, particularly when the product has not been used for a long period of time, possibly making the device completely unusable.
Patent Application WO 92/10727 describes a dosing head comprising a fixed-volume dosing chamber which can be moved from a filling position to a dispensing position, in which one or more outlets are exposed so as to allow the product to flow out under gravity. Such a system is not suitable for dispensing high-viscosity products.
Patent FR 674,613 describes a dispensing head which does not allow the quantity of dispensed product to be dosed.